Installation of fiber optic cables routinely involves burying the cable underground. Locating such buried fiber optic cables years after installation is often problematic. Without knowing a precise location of a buried fiber optic cable, servicemen may inadvertently sever the cable when installing or servicing a utility line, such as a sewer, waterline, gas pipe, or electrical cable.
One conventional approach to making a buried fiber optic cable detectable is to circumferentially encase the cable in a continuous shield, such as a flexible metallic tube or a rigid conduit that coaxially surrounds the cable's optical fibers. However, such tubing based on convention technology can be expensive to manufacture and/or cumbersome to install in the field. In particular, complications can arise when a fiber optic cable is encased by a conduit or duct that is electrically continuous between the two ends of the cable.
On the other hand, conventional fiber optic cables often contain no metallic material. Conventional metal detectors cannot, therefore, readily detect such metal-free cables. Accordingly these cable are at risk of being damaged after burial.
In a typical application, each fiber optic cable end is connected to a terminal device, such as an electrically driven optical transmitter, optical receiver, or optical transceiver. The metal tube can carry unwanted voltage along the fiber optic cable, for example from one terminal device at one end of the fiber optic cable towards the other terminal device at the opposite end of the fiber optic cable. If a person contacts the tube, the person may receive a shock if the tubing is not properly grounded. Accordingly, such metallic tubes, ducts, and conduits are typically grounded at both ends of the fiber optic cable for safety and to reduce shock hazards. Such grounding involves significant cost and, if not properly installed, can fail.
Accordingly, to address these representative deficiencies in the art, what is needed is an improved capability for detecting a buried fiber optic cable. Another need exists for a method and apparatus for efficiently manufacturing fiber optic cables that are detectable when buried underground. Yet another need exists for an apparatus that can be disposed in a fiber optic cable to facilitate locating the cable without providing an electrically conductive path between ends of the cable. A capability addressing one or more of these needs would support increased usage of buried optical fiber and would reduce service disruption associated with inadvertently severed cables.